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  • #2281405

    Memory Management

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    by umer ·

    Hi

    1- The addres of page frame in RAM only has 20 bits, why is that?

    2-If page in Ram has to be swaped out to give another page a turn, how operating system will knowwhether it has to write the page back to disk

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    • #3376126

      Reply To: Memory Management

      by tech_wiz03 ·

      In reply to Memory Management

      1) a 20bit address allocates 1mb of memory the old standard from the pc-286 days where pageing memory was in 1mb extended chunks. Windows still uses this standard internally. allocating as many 1mb blocks as needed.

      the operating system keeps track of all allocated page frames both in ram and on disk pagefile when the needed page isn’t in memory it fetches the page from disk. to make room for the new page it swaps out non-recent pages to disk and ideally only updates the pages on the swap that have changed. In practice however windows writes all pages whether or not they have changed since last write since the pagefile may have reclaimed and used previous swap space since the swap space was last referred to.

      regards
      rick

    • #3376089

      Reply To: Memory Management

      by umer ·

      In reply to Memory Management

      This question was closed by the author

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